HR: 15:25h
AN: H42H-08    [PDF]
TI: Energy and Water Balance Partitioning With Vegetation
AU: * Cuenca, R H
EM: cuenca@engr.orst.edu
AF: Department of Bioengineering, Oregon State University, Corvallis, OR 97331-3906 United States
AU: * Cuenca, R H
EM: cuenca@engr.orst.edu
AF: Department of Civil and Environmental Engineering, University College Cork, Cork, 00000 Ireland
AU: Migliori, L
AF: Department of Civil and Environmental Engineering, University College Cork, Cork, 00000 Ireland
AU: O'Kane, P
AF: Department of Civil and Environmental Engineering, University College Cork, Cork, 00000 Ireland
AB: Vegetation coupled with soil moisture conditions are control mechanisms of hydrologic processes in a watershed, including evapotranspiration and infiltration. Persistence and feedback in partitioning of latent and sensible heat fluxes as a function of vegetation canopy and soil moisture conditions play a major role in the water balance of a watershed. Two complimentary experimental watersheds are discussed in this presentation. The 200 km2 lower Feale catchment is a low-lying peaty area in southwest Ireland that is subject to flooding. The effort to determine flood mitigation strategies has required development of a detailed hydrologic balance for the wet pasture study area. An eddy correlation system was installed in the Feale catchment in 2002 to measure components of the energy balance, including evapotranspiration, along with special sensors to measure other hydrologic variables particular to this study. The problems of data management, data quality control, individual instrumentation sensitivity, potential underestimation of latent and sensible heat and possible sources of energy balance closure errors for this wet environment and micrometeorological conditions are discussed. A complimentary data set from a Bowen ratio system experiment in a more arid grass environment in Oregon is also analyzed. Long-term, 20-min frequency data from the Oregon Evapotranspiration Investigation Plot (ETIP) from spring, summer and fall periods, including a special summer dry-down experiment, are analyzed for impacts of soil moisture content on daily Bowen ratio and ratio of measured grass evapotranspiration to a Penman-Monteith reference evapotranspiration. The gradual shift in partitioning of available energy between latent and sensible heat fluxes within a growing vegetative canopy with fully developed root zone illustrates the complexity of the processes and the difficulty of determining functional relationships for the control processes.
DE: 1655 Water cycles (1836)
DE: 1818 Evapotranspiration
DE: 1836 Hydrologic budget (1655)
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting